This invention relates to elastomeric articles such as gloves, and, more particularly, to such elastomeric articles specially treated to make them easy to slip on.
Highly elastic articles such as surgical and examination gloves have traditionally been made of natural rubber latex in order to utilize its combination of good elasticity and strength. However, some persons are allergic to natural rubber latex, and in addition natural rubber latex is susceptible to environmental damage such as ozonation. For many years, the only available alternatives to natural rubber latex were synthetic elastomers which did not produce allergic reactions, but which also tended to exhibit insufficient elasticity and strength, as well as susceptibility to ozone degradation in some cases.
An important advance in this area was the development of medical gloves made of S-EB-S (styrene-ethylene-butylene-styrene) synthetic elastomer block copolymers, as disclosed in U.S. Pat. Nos. 5,112,900 and 5,407,715. Articles such as gloves are readily dip-formed from such block copolymers, without the occurrence of pinholes that can result from impurities found in natural rubber latex. The articles have substantially the same elastic and strength properties as natural rubber latex, are hypoallergenic, and are not subject to ozonation damage. Gloves made of S-EB-S block copolymers are available commercially from Tactyl Technologies, Inc., Vista, Calif.
Tightly fitting elastomeric articles such as gloves and condoms, whether made of natural or synthetic elastomers, can be difficult to don. The elastomer action of the material of construction, its friction with the skin of the user, and the perspiration on the body of the user act in combination to make it difficult to slip the article on. To overcome this problem, it has been conventional practice to apply a powdered lubricant to the surface that is to contact the body of the user, such as the inside of the glove. As an example, epichloro-hydrin treated maize crosslinked starch is a common powder applied to the inside of elastomeric gloves during manufacture, to permit them to be more readily slipped onto the hand of the user.
The use of a powdered lubricant on the elastomer is operable, but has drawbacks in specific situations such as the case of surgical gloves. If some of the powder escapes from the inside of the glove into the surgical environment, as for example if the glove is torn during the surgery, the powder may enter the surgical wound to cause further complications for the patient. The powder may carry infectious agents, or the patient may be allergic to the powder.
Various other techniques are known for use with surgical gloves to improve their donning characteristics. These techniques include, for example, manufacturing the glove from a modified latex, using an inner layer of a hydrophilic polymer, applying a slip coating to the inner surface of the glove, providing lubricating particles on the inner surface of the glove, and other approaches.
While these techniques for producing powder-free gloves are perhaps operable in their conventional applications, the present inventors have found that they are not fully satisfactory for use with gloves made of the synthetic S-EB-S block copolymers and some other materials of construction. There is, accordingly, a need for an improved approach for providing a powder-free article such as a glove with acceptable donning characteristics. The present invention fulfills this need, and further provides related advantages.
The present invention provides an elastomeric, powder-free article having excellent donning characteristics. The article is preferably made using a substrate of synthetic elastomer that exhibits good elasticity and strength, is hypoallergenic, is resistant to environmental degradation, is producible by dip forming, and is otherwise acceptable for use. These properties are not adversely affected by the treatment and structure that provide improved donning characteristics, both initially and after aging of the article. The treatment for improving the donning characteristics is fully compatible with the forming of the underlying substrate. The approach of the invention is operable with a wide variety of substrate materials including, but not limited to, those made of natural rubber latex and those made of S-EB-S block co-polymers such as those disclosed in U.S. Pat. Nos. 5,112,900 and 5,407,715.
In accordance with one aspect of the invention, an elastomeric article comprises a substrate body made of an elastomeric material such as natural rubber latex or a mid block saturated styrene block copolymer such as an styrene-ethylene-butylene-styrene block copolymer, and a donning layer overlying at least one side of the substrate body. The donning layer comprises 1,2 polybutadiene, preferably syndiotactic 1,2 polybutadiene. Optionally, a surfactant-containing layer overlies the donning layer and comprises a cationic surfactant, or a cationic surfactant and a silicone antifoam. Operable surfactant-containing layers comprise an alkyl dimethylbenzyl quaternary, an alkyl trimethyl quaternary, a dialkyl dimethyl quaternary, sodium lauryl sulfate, and/or pyridinium chloride. The silicone antifoam is preferably polydimethyl siloxane emulsion.
In accordance with another aspect of the invention, an elastomeric article comprises a substrate body made of an elastomeric material, preferably a mid block saturated styrene block copolymer such as an styrene-ethylene-butylene-styrene block copolymer, and a donning layer overlying at least one side of the substrate body. The donning layer comprises a chlorinated mid block unsaturated block copolymer such as a chlorinated styrene diene block copolymer, preferably chlorinated styrene-isoprene block copolymer. The styrene-isoprene block copolymer preferably has a polystyrene block content of from about 10 to about 20 percent by weight of the total copolymer weight and an end block polystyrene molecular weight of at least about 5,000 grams per mole. A surfactant-containing layer overlies the donning layer and comprises a cationic surfactant, or a cationic surfactant and a silicone antifoam. The cationic surfactant is preferably an alkyl dimethylbenzyl quaternary, an alkyl trimethyl quaternary, a dialkyl dimethyl quaternary, sodium lauryl sulfate, or pyridinium chloride. The silicone antifoam is preferably polydimethyl siloxane emulsion.
The elastomeric article is manufactured by preparing the substrate body made of an elastomeric material by any operable technique, most preferably dip forming. The donning layer is applied to the substrate body by any operable technique, most preferably by dipping the substrate body into a solution of the donning layer polymer, and thereafter chlorinating the donning layer. The surfactant layer is applied over the donning layer by any operable technique, most preferably by dipping the substrate body and overlying donning layer into a solution of the surfactant.
The elastomeric article of the invention has excellent elastic and strength properties, is readily manufactured, and can be donned easily without the presence of any powder. In the case of the preferred S-EB-S substrate body, the article is hypoallergenic and is resistant to environmental degradation such as ozonation. The donning layer does not crack or peel from the substrate body during storage or service. Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The scope of the invention is not, however, limited to this preferred embodiment.